ABSTRACT
The proper selection of valves is a major consideration in the design and operation of a
cryogenic process system. Basic valve-designs may appear no different than those available
for other chemical processes, but the very fact that cryogenic valves have to operate effi-
ciently, smoothly, and with no leakages at temperatures between 100 K and down to 4 K
imposes exacting specifications in the design and materials of fabrication. Obviously, during
start-up of any project, ambient temperatures will be close to 300 K. Furthermore,
capital costs cannot be ignored. The overall cost of valves runs between 20% and 30%
of the total piping costs. But undersizing magnifies pressure losses across the valve. The latter
is unacceptable in the expansion (throttling) of cryogens where precision is necessary to
avoid vaporization, and achieve a specific precalculated temperature drop downstream of
the valve.
